In this paper, a comprehensive analysis and research is carried out on the actual railway traffic engineering area in Liaoning Province. Laser displacement sensor is used to design the deformation detection system of subway tunnel structure, which can give full play to the function of three-dimensional laser scanning technology. Finally, the following conclusions are drawn. In the tunnel deformation monitoring project, three-dimensional laser scanning point cloud data is used to extract tunnel section. The collection period is 10 periods and the time span is 55 days. The characteristic section of a metro tunnel in Liaoning Province is analyzed and monitored. From the third to the sixth period, it is found that the load and settlement of the tunnel will change greatly with the continuous construction of super high-rise buildings, of which the latter is gradually in a stable state. Combining with the actual engineering data, the settlement value of the observation period is the largest at 3.35 mm. Analyzing the results of the three-dimensional laser scanner and the traditional level settlement detection, it is found that the variation trend and variation of tunnel settlement can be approximately the same. This shows that the method proposed in this paper can analyze tunnel cross-section deformation more comprehensively and intuitively.